Telephoto lens objective

ABSTRACT

The invention contemplates a telephoto-lens construction comprising four parts, one or more of which is a multiple-element part, and so devised as to achieve superior achromatic quality over a wide field of view, within a structural length which is less than the focal length. This result is achieved by following a particular schedule of regions from which to select optical glasses for the respective parts, or for the respective multiple elements of one or more of such parts, and by forming lens elements with such selected glasses in accordance with a particular schedule of refractive powers.

Determann et al.

1 1 TELEPHOTO LENS OBJECTIVE [75] Inventors: Fritz Determann,Oherkochen;

Heinz Zajadatz. Aalen, both of Germany [73] Assignee: CarlZeiss-Stiftung, Oberkochen Germany [22] Filed: Feb. 14, I973 [21] ApplNo.: 332,416

[30] Foreign Application Priority Data Feb 22, 1972 Germany 2208163 [52]US. Cl. 350/214; 350/215; 350/216 [51 l Int. Cl. G02b 9/00 [58] Field ofSearch 350/214, 215, 216

[56] References Cited UNITED STATES PATENTS 2 778 272 1/1957 Reymond350/214 1 1 May 13,1975

Yumji .4 350/214 Tolle 350/215 Primary Examiner-Ronald L. WibertAssistant E.\aminer-Conrad Clark Attorney, Agent. or FirmNichol M.Sandoe [57] ABSTRACT CI'S.

11 Claims, 7 Drawing Figures Iris 1 TELEPHOTO LENS OBJECTIVE The presentinvention relates to a telephoto lens formed of a converging part of thesystem which faces the side of the longer ray distance, followed by adiverging part, a converging part following same at a larger distanceaway, and then finally again a diverging part.

Telephoto lenses of the indicated type make it possible to reduce thestructural length to values considerably less than the focal length ofthe lens. The expression structural length" as used herein is to betaken to mean the distance ofthe image plane from the first vertex ofthe first lens element in the system.

Constructions of this type known up to the present time exhibit typicalerrors with respect to color correction, which errors limit their use.As is known, in lenses of long focal length, the secondary colorspectrum of the longitudinal aberrations as well as that of thetransverse aberrations is always very disturbing. It is even larger, andtherefore more apparent, in the known telelenses of shortened structurallength than in simple achromatics or apochromatics of the same focallength but larger structural length.

The object of the present invention is to provide a tele-lens ofimproved quality by eliminating the secondary color spectrum whichconstitutes the decisive disadvantage of the known types of tele-lenses.At the same time, it is an object to obtain monochromatic correction ofequivalent quality, for such relative apertures as are ordinarilyexpected for the corresponding focal lengths.

These objects are obtained in accordance with the invention by aspecial, unorthodox manner of selecting optical materials, which willhereinafter be referred to generally as glasses", in combination with anadvantageous distribution of refractive powers. The glasses are selectedin particular on the basis of their relative individual dispersions P**in the blue portion and P* in the red portion of the spectrum. In thisconnection, we have P** Np N /Ny lv and 1 N N /N N in which N is theindex of refraction and the subscripts designate the wavelengths oflight in accordance with the Schott catalog. The characterizing of theglasses on basis of P** and P* has been established by Herzberger. Healso sets forth rules as to how the secondary spectrum of a lens can beentirely eliminated in the paraxial region by means of thischaracterization (superachromasia). Together with Pulvermacher, he givesfurther rules as to how the paraxial difference in enlargement can alsobe corrected. These rules, however, relate only to the correction ofparaxial errors. Other errors such as, for instance, sphericallychromatic aperture errors (Gauss errors) are not affected thereby.Since, however, a superachromatic correction on the axis is onlymeaningful in combination with an extremely good correction of all otherpicture defects such as spherical aberration, image shell curvature,astigmastism, coma and distortion in the entire picture field, bothmonochromatically and in particular chromatically, and possibly evensuperachromatically, the said rules of Herzberger and Pulvermacher arenot sufficient for the production of a lens which meets demands forhighest quality and, accordingly, are used only in special cases wherevery small picture fields are to be corrected. Thus, particularly in thecase of the known lenses with longer focal lengths, the large secondaryspectrum has up to now so greatly overlapped a high monochromaticcorrection, obtained possibly at high expense, that such an expense canbe considered meaningless for the monochromatic correction, inasmuch asthis secondary spectrum exists not only in the center of the picture butin particular for all lateral picture errors in different forms ofappearance, and, as a matter of fact, to a good part entirelyindependently of any good color correction possibly present on the axis.Here, there actually exists another deficiency for which the presentinvention for the first time provides a satisfactory remedy.

In accordance with the present invention, there are used for theconstruction of the said tele-lenses as a rule only optical materialsselected from the following five very small ranges of the P** P* glassranges:

Range 1: P** =l.933 10.02] P 1.749 :(Hlltl Range 2: P =-l.72-'$ i().02|P* 1.787 (lllltl Range 3: P =l.863 iOUZl P* I 1.765 t 0 (H0 Range 4: P**=-2.09l 1:0.02l P* L727 2 0.010 Range 5: P l.925 1:0.02l P* I l.'15l (Itllli With regard to the relative size of the five ranges. it may bementioned that the width of variation of the values of all Schottglasses range for P** from 124 to l.698 and for P* from L to l.90.

All powers of the individual lenses which enter into question must beadapted to the glass selected, and the ratio of structural length tofocal length desired also in fluences the powers. The powers can bederived from the refractive-power characteristics A. B, C. D, E, whichfor this purpose are divided by the structural length desired. In thisconnection, the inventive quality results only if the following powercharacteristics are complied with (for a-refractive power of the entiresys tem of 1.0):

The invention is illustrated by five specific examples provided at theend of this specification, and the accompanying FIGS. 1 to 5 are opticaldiagrams which respectively apply to these five examples. The remainingFIGS. 6 and 7 are similar diagrams, illustrating systems as in FIGS. 1to 5 and having additional combining elements. in all diagrams, thefirst vertex is indicated by a heavy dot, with the legend FV, and thediaphragm location is labeled Iris.

In general, tele-lens systems of the invention comprise four parts, someof which may be made of multi ple elements; these four parts areconsistently designated with the respective legends T T T T In the firstpart (T,); as seen in the direction ofthe path of the light, there isfirst of all provided a diverging member, primarily of glass of range 1,with a refractive power proportional to A; this is followed by aconverging member, primarily of glass from range 2, with a refractivepower proportional to B. Part 2 (T then follows, being a divergingmember (or members) of glass, primarily from range 3, with a power ofrefraction proportional to C. This is followed at a larger distance awayby part 3 (T in the form of a converging member (or members) of glass,taken primarily from range 4, with a refractive power proportional to D.Finally, at a still greater distance away, part 4 (T follows, being adi- 3 verging member (or members) of glass, primarily from range 5 witha refractive power proportional to E. The proportionality factor for therefractive power characteristics A, B. C, D, E is always the reciprocalof the structural length.

For better compensation of the errors of higher order, it is oftensuitable to provide individual members of the above enumeration not onlyby using glasses selected from the glass ranges primarily indicated forthe purpose. but also by additionally using associated weaker lensesselected from among the other four indicated glass ranges; suchassociated lenses in themselves or together with other lens elements ofthe particular part may also be secured at cemented adjacent surfaces[as for example at d between adjacent surfaces R R- in FIG. I), but theyalways fall within the limits of the stated refractive power for theparticular part, as will be seen from the accompanying diagrams for therespective illustrative examples given below. For instance, it isadvantageous, for a larger angle of view and for a larger relativeaperture, to make part 3 (T from two or more lens elements of theabove-indicated glass ranges; thus, for two disclosed embodiments of theinvention, it has been satisfactory to provide a part 3 (T lens ofrefractive power D by using a first converging lens of glass of range 4with refractive power D, and a following second converging lens of glassor range 3 with the refractive power D where D, -l- D is propor tionalto D. In two other embodiments of the present invention, part 3 (T issplit to comprise three elements, namely, converging lens of glass ofrange 4 with refractive power D, a subsequent meniscus-shaped to D. Veryslightly refractive associated lenses can in exceptional cases beprepared without great damage to superachromatism in favor of othereffects using glasses of other ranges, as illustrated by Example 2.

For each part of the objective lens. there is the possibility ofcementing the lens elements together; additionally, a cement surfacebetween part 1 (T and part 2 (T is also possible. It is also possible inall parts (T T,) to simulate the properties of the glasses indicated forthese parts by free-standing or cemented combinations of two or moreglasses which may be of one or more entirely different ranges. Thesepossibilities necessarily result from the invention, as illustrated byExamples l and 2.

The tables below indicate the design data for five Examples, designatedI to V, in support of the elements of the claims and their practicalrealization, as further illustrated by FIGS. 1 to 5, respectively. Inall these figures of the drawings, the radii R entered bear assubscripts the numbering of the optical areas in the data tables. Lensthicknesses and air spaces are designated by (d) and are also providedwith subscripts in the same continuous numbering as the data tables.Furthermore, the individual lens elements in each system are designatedL, and the numbering of the subscripts for L corresponds to thearrangement of the lenses in the direction of the incident light.Further, as already explained, there are indicated in the figures whatlenses or lens combinations represent the individual members T to T, ofeach particular telephoto-lens system.

For the embodiments of the invention shown in FIGs. 6-7, moreabbreviated data tables are appended. These figures merely showpossibilities of combining weaker lens of glass of range 3 (with thecurvature towards the 35 lenses or flat plates P for the construction oflens sysincident light) with refractive power D and a follow terns fromthe preferred glass ranges or the combinaing converging lens of glass orrange 2 with the refraction of glasses of still further ranges to obtainthe proptive power D;,, where D D; D is again proportional erties of theglasses indicated.

Example I Focal length 1.0 Back focus 0.4480 Structural length 0.8226Relative aperture l:6.3 Half of angular field 3.7

Lens refractive Refractive Glass powers X power characterrangestructural length istics range Areas Radii Thicknesses Glass P** P* LensPart No. for color d l .l7329 .012897 LaFN B l.932l L748) l\ l -.76S2l6A 2 .13765 .000512 I 3 .l3667 .036726 Fluor l.7237 1.7873 2 2 3.282835spar 4 .48339 .05 l843 5 .25375 .010078 LaF l.8623 l.7634 3 2 3 2.6642856 1.26255 .l40754 7 1.35693 .0l3l53 F ll 2.()746 1.7289 4 3 4 2.076017 8.29943 102149 9 .|lU .OO649I LF 3 l.92l7 1.75l9 5 4 5 2.2l7200 IO-.68992 Color d" in this and all tables refers to Helium-line d. at587.6 mg.

Example II Focal length l.() Back focus .4926 Structural length .8875Relative aperture l:5.6 Half of angular field Lens refractive Refractivepower Glass powers X characteristics range structural length range AreasRadii Thicknesses Glass P** P" Lens Part No. for color d l .ZOSOU.(ll82l3 LaFN 8 l.932| L748) l\ I .563798 A 2 .16759 .006805 l 3 17249.044232 Fluor- -l.7237 1.7873 2 2 3.317877 s ar Example 1! ContinuedFocal length 1.0 Back focus .4926 Structural length .8875 Relativeaperture 1:5.6 Half of angular field 8.5"

Lens refractive Refractive power Glass powers X characteristics rangestructural length range Areas Radii Thicknesses Glass P P" Lens Part No.for color d 4 .32723 .008006 5 .29588 .013410 LaF 20 1.8623 1.7634 3 2 3-2.462950 C 6 1.48328 .138501 7 1.B1388 .030822 F 11 2.0746 1.7289 4 41.491605 D 8 .30895 .012609 3 D 9 .51862 .032824 LaF 20 1.8623 1.7634 53 901938 0.; 10 2.21882 .081259 11 .20948 .008206 LF 8 l.92l7 1.7519 6 45 3.000638 E 12 .83385 EXAMPLE Ill Focal length 1.0 Back focus .4018Structural length .9793 Relative aperture 1:4 Half of angular field 8.5

Lens refractive Glass powers X Refractive power range structural lengthcharacteristics Areas Radii Thicknesses Glass P" P* Lens Part No. forcolor d range 1 .27517 .023522 LaFN 8 l.9321 1.7489 1 1 .581383 2 .21699.005001 1. 3 .22659 .069007 Fluor- -1.7237 1.7873 2 2 2.785419 8 spar 4-.42376 .009281 5 .40584 .019002 LaF 20 l.8623 1.7634 3 2 3 l.958457 C 62.18543 .200821 7 1.33990 .025403 TiF 5 2. 1090 1.7312 4 4 1.187766 D 8.76456 .075128 9 .15365 .026163 LaF 20 l.8623 1.7634 5-3 3 .121210 D, D10 14714 .027283 l l .9010l .018002 Fluorl.7237 1.7873 6 2 1.104415 D;.

spar 12 .27123 .065287 13 -.17113 .013601 LF 8 1 .9217 1.7519 7 4 5-2.780549 E 14 1.26501 D +D,+D,,=2.4l3391 Example 1V Focal length 1.0000Back focus 0.5077 Structural length 0.8477 Relative aperture 115.6 Halfof angular field 54 Lens refractive Glass powers X Refractive powerrange structural length characteristics Areas Radii Thicknesses Glass P"P* Lens Part No. for color d range 1 .19218 .014321 LaFN 8 1.9321 1.7489l l .8851B4 A 2 .14620 .000326 1 3 .14516 .043891 Fluor- 1.7237 1.7873 22 +3.111989 spar 4 .57788 .050863 5 .29807 .013293 LaF 20 l .8623 1.76343 2 3 2.l56420 C 6 2.73377 .124650 7 3.64420 .016052 TiF 5 -2.l0901.7213 4 4 +1.846159 D 8 .29384 .005142 3 D 9 .78186 .014622 LaF 201.B623 1.7634 5 3 +1.245l44 D 10 l.13650 .049158 11 -.22l27 .007650 LF 8-l.92l7 1.7519 6 4 5 3.462688 E 12 .37257 Example V Focal length 2 lBack focus 0.4093 Structural length 0.9789 Relative aperture l:4 Half ofangular field 2 8 6 Lens refractive Glass powers X Refractive powerrange structural length characteristics Area Radii Thicknesses Glass PMP* Lens Part No. for colord range 1 0.27154 0.02138l LaFN 8 1.93211.7489 1 1 *1144957 A 3 021111 0003031 1 3 0.22041 0.069386 Fluorl.7237L787} 2 2 2879370 B spar 4 0.403- 0 005 244 5 0.40340 0.017750 LaF :0186i 1.7634 1 2 3 2.l 1 1017 C s 1.49am 0. 186375 7 0.79339 0020625 F ll2.(J74fi 1,7289 4 4 L34 l 541 D s -1042ss 0.033909 9 0. l 527i 0.023398LaF l .8623 l.7634 5 3 0028855 D2 D 10 0.14417 0.035500 ll 1 W4700.02259] Fluor *l.7237 L787} 6 2 l 20055] =1) spur 1: #120461 0.06373913 at 1776: 0.010085 LF s 1.92 17 1.7519 7 4 5 2.882731 E 14 47314 fj+fi ,+l'j 3 5711047 DALI Table to FIG. 0 7 that from the opticalmaterials so selected, lenses or I I PW 3 2 I Rflflgle lens groups areformed whose refractive powers, multi- Li Plinirs par 172.77 1:72-17} 2plied by the structural length assu me refractive power LY. 811F511 190th 7484 1 characteristics which. fora refractive power l.() for the1;: a: 1111: 1a.: 7 1... 1 11 207 1 7:89 4 A iii-18 1. L11F20 1.862317634 3 B 2 i 7 L. Fluorspar "17237 1.7873 2 7 v 1. LFR 1.9217 1.751 1 5C 7-435 U59 l11 ('vmhmauon ilikc Lil-201 D z i E 2.90 i 0.69, Dam 111MBFIG 7 1S structural length being taken as the distance from the E Jr lfirst vertex of the first lens to the image plane of the ob- U0 I A t tr L; LaFZtI 4 L862} 1,7634 3 ectlve; the first part comprising a firstmember primarti f ily of material of glass Range 1 and having arefractive 33 4 3;; 1 power proportional tothe value A, and a secondmem- LFR l 93l7 177519 5 ber of matenal primarily from glass Range 2 andhaving P m7 17221 1.8697 g 40 What is claimed is:

l. A photographic telephoto lens objective, comprising a convergingfirst part facing the side of the longer light distance. a followingdiverging second part, a converging third part following at a greaterdistance away, and a final diverging fourth part, characterized by thefact that the optical materials for all lenses with the exception ofassociated lenses which are almost free of refractive power are selectedfrom five ranges of the P** P* presentation, in accordance with which:

where N is the index of refraction and the subscripts F. C. 1' and Irepresent the wavelengths oflight for the blue and red hydrogen linesand for the ultraviolet and infra red mercury lines. respectively. andthat for Ranges 1 to S the following limits apply:

Range l1 P I l )3? 1002i P l 74 0.0l0 Range 2. P L724 t 0.02] P* L787 20 (till Range 3. P 1.863 1002i P L765 i 0.0l0 Range 4 P I 2.09! :(HlllP" 1727 10.010 Range 5 P I l 925 10.02l P* 2 i751 i0.0l0

a refractive power proportional to the value B; the second partcomprising a member primarily of material of glass Range 3 and having arefractive power propor tional to the value C; the third part comprisinga member primarily of material of glass Range 4 and having a refractivepower proportional to the value D; the fourth part comprising a memberprimarily of material of glass Range 5 and having a refractive powerproportional to the value E; the proportionality factor being thereciprocal of the structural length of the objective.

2. An objective lens according to claim 1, characterized by the factthat the third part consists of a lens of glass Range 4 and having arefractive power proportional to D.

3. An objective lens according to claim 1, characterized by the factthat the,third part consists of a first lens element of glass Range 4with a refractive power proportional to D and a second lens element ofglass Range 3 with a refractive power proportional to D in such mannerthat D D D.

4. An objective lens according to claim 1, characterized by the fact thethird part consists of a first lens element of glass Range 4 with arefractive power proportional to D a following meniscus element which issubstantially without refractive power and is arched towards the light.said meniscus element being of glass Range 3 with refractive powerproportional to D and a following lens element of material from glassRange 2 with a refractive power proportional to D in such manner that 1D1);, l).

5. An objective lens according to claim 1, in which two parts of theobjective lens comprise adjacent multi- 8. An objective lens accordingto claim 1. characterized by the fact that its structural datacorrespond to the values set forth in the following table:

Example 111 ple elements, each of which elements is of a different gm58I Focal length 1,0

6. An UbjCCIWe lens accordlng to claim 1, character- Back focus 411114ized by the fact that its structural data correspond to f l l lmgh 19793elatlve aperture 1.4 the values set forth in the lollowmg table: Hlillufangular field 8.5

. Example l Areas Radii 'l'hicknesses Lens Part Glass 1 27517 1123522 ,15 Fecal length 2 .21699 .OtlSlltll l\ 1 l M x B l dck A1448 3 32659069007 3 Huorspar Structural length 0.822(1 4 4j37 ug-1m Rellllivsoverture lib-3 t5 5 .4n5s4 1119002 3 2 LaF In Half of angular field 3.7"1 2.1 543 jflmtjl 7 1.33990 .025403 4 'l'iF 5 Areas Radii ThicknessesLens Part Glass 8 76456 075128 9 .15365 .036163 5 3 LaF Ill 1 .17329.0128)? 1 LaFN a 10 14714 1127283 3 137 5 105 1 ll .9Ult)l .018002Flunrspar .1 .1366! 036716 2 fluorspar 30 11 137123 @5387 4 4 339 051 4313 .17113 .(1131'101 7 4 LF ii 5 25. 75 moms 3 2 LaF 14 l 3650' h1.26255 .140754 7 35693 (H3153 4 3 F H Lens relraetive RLlfllCIHC q 1Glass powers strucpouer char 2 5 4 LF 8 Range tural length foracteristics 10 Lens P P* No, color d range 1 1 l.9321 1.7489 1 .51i1383A Lens refractive Refractive 2 7217 L787} 2 1785419 8 Glass powers Xstrucpower char 3 36:23 17614 3 9584 range tural length for acteristics4 1,7213 4 M37766 I) Lem N9 Color 11 range 5 -|.8623 1.7634 3 .12121u=n.1)

'30 (1 l.7237 1.7873 2 1.104415 DI, I 19331 197439 I A 7 |.92|7 1.7519 s-2.78(i549 E 2 1.7237 1.7873 2 3282835 B '1 1.8623 1.7634 3 -2,6fi4285 C4 2.0746 1.7289 4 2.076017 D s A9217 1.1519 5 *2 217200 E. Where D,+D-l-l) 2.413391 D.

9. An objective lens according to claim 1, characterized by the factthat its structural data correspond to 7. An objective lens according toclaim 1, characterh vames Set f nh i m f ll i bl ized by the fact thatits structural data correspond to E l xample 1\ the values set forth inthe following table:

Example 11 4Q Focal length 1110110 Back focus 0.05077 Structural length0.8477 Focal length 1.0 Relative aperture 115.61 Back focus .4 36 Halfof angular field 5.4" Structural length .8875 Relative aperture 115.6Area Radii Thicknesses Lens Part Glass Halfof angular field 8.5

1 119218 .014321 I LaFN 8 Areas Radii Thicknesses Lens Part Glass 2114620 .000326 l 3 .14516 .0438)! 2 Fluorspar 1 211500 018213 1 LaFN s 4957788 1150863 2 1 75g 00 805 5 -129807 1113293 3 2 LaF 20 3 17241:1144232 2 fluorspilr 173377 124650 4 32723 003mm 7 3.64420 016052 4 TiF5 5 -.295ss 1113410 3 2 LaF 2n 8 "29384 6 l 48px nxgm 9 78186 1114622 5LaF :0 7 l g a 4 F H 10 1.13650 1149158 11 22127 .(107650 6 4 LF 1% s.3us9s .012609 3 17,57 9 51862 .032824 5 LaF 20 m 2 3'88: (Ill l 259Lens refractive Refractive l "131F948 6 4 8 Glass powers X struc powercharx3385 Range tural length for acteristies Q k 1 s L Lens refractiveRefractive Lu P P Ml u lm d r Inge Glass poners X struc power ehar- .432 74 4 5 84 A Range tural length for acteristics 1 7237 r7873 1 +3 11939 Lens P P" No. color ll range 3 8(,13 {76,34 3 -2 15642 C 4 2.1U)ll1.7213 4 +1,84615U=IJ 1 1.J3Z1 1.741%? I .5o7 :|1'l A 5 "1.8623 1.7634 3+1.245144= D I -17237 1,7873 2 3.3171477 B 6 1.9217 1.7519 5 11462688 E3 -1 8623 1.7(134 3 1.462950 C 4 3.(l74h 1.7139 4 1.-1'-)!o05=l) 5 1 6237M4 3 .9(l193l =1l, D h 1 :21? i 7519 s KlKlllhJX 1-; 6g Whcrs 1 1+3-0913U3 where D +1) 3.393543 =1).

10. An objective lens according to claim 1. characterized by the factthat its structural data correspond to the values set forth in thefollowing table:

Example V Lens rcfruclhc Refractive Glass powers X strucpower Chill-Rnnge tuml length fur ucleristics FOClli iengih H) 1 1 gawk focus UAW LuI P No. LUIOI d rimge Y 1 91 1 1 74119 1 #1114491? A Rel-11mg aipcnurg j|:4 41 7E7 {787} 7 a 87912; B Hailfol angular held 811 3 1 M-)- 1 7m H{017 C Areas. Radii l'hickncascs Lens Purl (Haas 4 2.0746 1728) 41.341541 I),

5 H613 117633 3 (HD8855 =1) D i M17154 0.021381 i LuFN X h -i7]37 117373I LZUUSSI =1) 2 1121111 (Hllllhfil m 7 19217 1.751 5 -2,x1127.11 E

9 33 113 :2212 4 F H where 1),+1). +1) 2.5711947 D.

x 315 (11111 1 5 7 ll. An objective lens according In claim 1, in whichmm: of the parts ufthe objective lens comprises at least I] 1l10471|111121191 (1 Fluurspur \hrcu clcmcnls. each of which elements is 0f 11different I2 (].2696! Ullb373) gl l3 (L17761 (LUIUORS 7 4 LF 8 (ill

1. A photographic telephoto lens objective, comprising a convergingfirst part facing the side of the longer light distance, a followingdiverging second part, a converging third part following at a greaterdistance away, and a final diverging fourth part, characterized by thefact that the optical materials for all lenses with the exception ofassociated lenses which are almost free of refractive power are selectedfrom five ranges of the P** - P* presentation, in accordance with which:2. An objective lens according to claim 1, characterized by the factthat the third part consists of a lens of glass Range 4 and having arefractive power proportional to D.
 3. An objective lens according toclaim 1, characterized by the fact that the third part consists of afirst lens element of glass Range 4 with a refractive power proportionalto D1 and a second lens element of glass Range 3 with a refractive powerproportional to D2, in such manner that D1 + D2 D.
 4. An objective lensaccording to claim 1, characterized by the fact the third part consistsof a first lens element of glass Range 4 with a refractive powerproportional to D1, a following meniscus element which is substantiallywithout refractive power and is arched towards the light, said meniscuselement being of glass Range 3 with refractive power proportional to D2,and a following lens element of material from glass Range 2 with arefractive power proportional to D3, in such manner that D1 + D2 + D3 D.5. An objective lens according to claim 1, in which two parts of theobjective lens comprise adjacent multiple elements, each of whichelements is of a different glass
 6. An objective lens according to claim1, characterized by the fact that its structural data correspond to thevalues set forth in the following table:
 7. An objective lens accordingto claim 1, characterized by the fact that its structural datacorrespond to the values set forth in the following table:
 8. Anobjective lens according to claim 1, characterized by the fact that itsstructural data correspond to the values set forth in the followingtable:
 9. An objective lens according to claim 1, characterized by thefact that its structural data correspond to the values set forth in thefollowing table:
 10. An objective lens according to claim 1,characterized by the fact that its structural data correspond to thevalues set forth in the following table:
 11. An objective lens accordingto claim 1, in which one of the parts of the objective lens comprises atleast three elements, each of which elements is of a different glass.